Latest issue

International Review on Computers and Software - May 2007 - Papers

Adaptable and Adaptive Web Applications: From Design to Generation
Remote Control on Internet, Long Distance Experiment of Remote Practice Works, Measurements and Results
An Implementation of Dynamically Administered Role-based Access Control on the Web
Load Balancing and Static Placement/Scheduling Heuristic on Distributed Heterogeneous Architecture
On Cache Sizing in Multi-Core Cluster Architectures
Visually Mining Relational Data
CLOMAINT: A Data Mining Algorithm Applied in Maintenance SONATRACH
Speech Denoinsing and Arabic Speaker Recognition System Using Subband Approach
Improving Numerical Libraries
Aided-Computer Evaluation of Nonlinear Combination of Financial Forecast with Genetic Algorithm

International Review on Computers and Software - Papers

Adaptable and Adaptive Web Applications: From Design to Generation
by R. Ben Djemaa, I. Amous, A. Ben Hamadou

Abstract - Engineering adaptive Web applications imply the development of content that can be automatically adjusted to varying client devices and user preferences. To meet this requirement, we present in this paper an audience-driven approach for adaptive web applications called GIWA. GIWA‘s target is to facilitate the automatic execution of the design and the automatic generation of adaptable web interface. The GIWA design methodology guides the designer through different steps of the design process, each of them yielding a specific model that is being interpreted by the GIWA tools to achieve the objective of automatic presentation generation. The GIWA methodology is based on different step: requirement analysis, conceptual design, adaptation design and generation.

Keywords: Adaptive Web Application, GIWA, design, generation.

Remote Control on Internet, Long Distance Experiment of Remote Practice Works, Measurements and Results

by L. Kaddour-El Boudadi, J. Vareille, P. Le Parc, N. Berrached

Abstract - The aim of our work is to control remotely mechanical systems which have nowadays local controls. With the development of the e-technologies, improvement of the network in term of time and band-width, the remote control will be common and will be made using networks without true quality of service, even unpredictable like Internet. In a first part of this paper, we are presenting some existing applications we have used. In a second part, we are describing generic software architecture to realize such remote control and a methodology to take into account the unpredictable nature of the communication media. In the third part we present experimental results of long distance remote control.

Keywords: Remote Control, Internet, Methodology, Reliability, Networks.

An Implementation of Dynamically Administered Role-based Access Control on the Web
by A. K. Mattas, I. K. Mavridis, I. G. Pagkalos

Abstract - Access control administration regulates and enforces the definition of the components of an access control system by authorized administrative users. The shortcomings of classical access control models, as they are applied in today’s Web-based applications that are commonly used in collaborative and distributed enterprise environments, can effectively be addressed by dynamic administration. In this paper, the implementation and application of the DARBAC (Dynamically Administering Role Based Access Control) model in the banking sector is demonstrated. By this demonstration, the benefits that are related to improvements in the administration of role-based access control (RBAC) and provision of tight and just-in-time access control without jeopardizing the simplicity of administration are clearly revealed.

Keywords: Computer security, Access control, RBAC, DARBAC.

Load Balancing and Static Placement/Scheduling Heuristic on Distributed Heterogeneous Architecture
by R. Saouli, M. Akil, T. GrandPierre

Abstract - In this work, we are concerning by the improvement of optimized static heuristic in distributed and heterogeneous architecture. Thus, in order to take into account the load-balancing criterion, a need for a dynamic model is related to the use of heuristic based on list scheduling. The greedy list algorithms are well adapted, for they help the designer to rapidly obtain an efficient implementation and so to shorten development cycle of an application. This paper presents a dynamic model based on agent concept, coupled with an off line (static) heuristic. Our model has been simulated in programming parallel environment Xpvm. We show the integration of our model in the transformations flow, that implicates a heuristic to generating a real time distributed executive. This integration will be implemented in system level CAD software tool called SynDEx which, is a seamless flow based on graphs transformations.

Keywords: multi agents systems, distribution/scheduling heuristics, static load balancing, AAA methodology, graph models, graph transformations.

On Cache Sizing in Multi-Core Cluster Architectures

by F. N. Sibai

Abstract - With multi-core products hitting every market segment, we focus on a 16 core cluster-based architecture comprised of 4 clusters. Assuming the L1 cache memories are private, we conduct SPEC92 simulations to study the effect of the block size, associativity, and cache size on the L1 cache hit rate. We observed significant drops in hit rate as the number of processors per cluster was increased from 1 to 4 with the largest drop occurring when boosting the number of processors from 1 to 2. This result leads to discouraging the design of small clusters with less than 4 cores per cluster and confirms that 4-core clusters are properly sized. In caches of at least 16KB and with 1024 blocks, we observed no significant benefit to increasing the associativity beyond 8, and identified the best block sizes to be 256B and 128B. Furthermore, hit rate improvements due to quadrupling the number of blocks and consequently the cache size were insignificant for block sizes of 64B or higher in caches with at least 256 blocks. For the SPEC92 benchmark, a 128KB 8-way set associative L1 cache with a block size of 64B is adequate.

Keywords: Multi-Core Architectures, 4-way CMP Clusters, Cache Performance.

Visually Mining Relational Data

by Y. Chiricota, G. Melançon

Abstract - Mining relational data often boils down to computing clusters, that is finding sub-communities of data elements forming cohesive sub-units, while being well separated from one another. The clusters themselves are sometimes termed “communities” and the way clusters relate to one another is often referred to as a “community structure”. Methods for identifying communities or subgroups in network data is the focus of intense research is different scientific communities and for different purposes. The present paper focuses on two novel algorithms producing multilevel community structures from raw network data. The two algorithms exploit an edge metric extending Watts's clustering coefficient to edges of a graph. The full benefit of the method comes from the multilevel nature of the community structure as it facilitates the visual interaction and navigation of the network by zooming in and out of components at any level. This multilevel navigation proves to be useful when visually exploring a network in search for structural patterns.

Keywords: Network analysis, Visual Interaction, Graph Mining.

CLOMAINT: A Data Mining Algorithm Applied in Maintenance SONATRACH

by R. Sid Ahmed, K. Salim, B. Hafida

Abstract - Plant maintenance produces daily large amounts of repairing data which contain hidden and valuable knowledge. This knowledge can be used for reduce the cost of maintenance, the time of intervention, in extreme case for saving the human life. In this paper, we designed an algorithm named CLOMAINT which is based on the ideas of the pattern-growth method for mining closed frequent calling patterns of SONATRACH maintenance database. First, by observing the features of the database and then extracting the attributes needed to be mined. Then, we merge the items to form an itemset, the algorithm is now applied to the transformed database. CLOMAINT is built on the basis of viewing knowledge discovery as an interactive and iterative process in order to optimize decision making. The quality of the knowledge discovered is evaluated. The experimental results show the knowledge of closed frequent patterns obtained is very useful and easy to interpret by the plant maintenance operators.

Keywords: closed frequent pattern, maintenance database, knowledge.

Speech Denoinsing and Arabic Speaker Recognition System Using Subband Approach

by Z. Sakka, A. Kachouri, M. Samet

Abstract - This paper proposes an efficient speech recognition method for Arabic language. A Hidden Markov Models based speech recognition system was designed and tested with automatic Arabic word recognition. The system is an isolated whole word speech recognizer and it was implemented as both a wideband speech signal and a subbands spectral recognition modes. We particularly discuss the selection of the most critical subbands for the speaker recognition task and the choice of an optimal division of the frequency domain. An appropriate selection of the most critical subbands shows that very good performances are still obtained with only half of the frequency domain, the strategy of decision rests on the individual decisions of recognizers in each subband. This recognition system achieved a 89.5% correct word recognition in the wideband mode, and 95.25% in subbands mode. A comparison between the various variants of analysis will be made to observe their performances.

Keywords: Arabic words, recognition, speech, subband, HMMs.

Improving Numerical Libraries
by K. Zotos

Abstract - The increasing availability of advanced-architecture computers has a significant effect on all spheres of scientific computation, including algorithm research and software development in numerical linear algebra. Linear algebra -in particular, the solution of linear systems of equations- lies at the heart of most calculations in scientific computing. Much of the work in developing linear algebra software for advanced-architecture computers is motivated by the need to solve large problems on the fastest computers available. For the past 10 years there has been a great deal of activity in the area of algorithms and software for solving linear algebra problems. The goal of achieving high performance on codes that are portablxe across platforms has largely been realized by the identification of linear algebra kernels, the Basic Linear Algebra Subprograms (BLAS). This paper discusses some of the developments in numerical libraries design.

Keywords: Numerical software, numerical software performance, software design.

Aided-Computer Evaluation of Nonlinear Combination of Financial Forecast with Genetic Algorithm
by A. Ozun, A. Cifter

Abstract - Complexity in the financial markets requires intelligent forecasting models for return volatility. In this paper, historical simulation, GARCH, GARCH with skewed student-t distribution and asymmetric normal mixture GRJ-GARCH models are combined with Extreme Value Theory Hill by using artificial neural networks with genetic algorithm as the combination platform. By employing daily closing values of the Istanbul Stock Exchange from 01/10/1996 to 11/07/2006, Kupiec and Christoffersen tests as the back-testing mechanisms are performed for forecast comparison of the models. Empirical findings show that the fat-tails are more properly captured by the combination of GARCH with skewed student-t distribution and Extreme Value Theory Hill. Modeling return volatility in the emerging markets needs “intelligent” combinations of Value-at-Risk models to capture the extreme movements in the markets rather than individual model.

Keywords: Forecast combination, Artificial neural networks, GARCH models, Extreme value theory, Christoffersen test.